1. Field of the Invention
The present invention relates to a signal output method, and an optical information recording medium having information recorded thereon by the signal output method.
2. Description of the Related Art
On an optical information recording medium (recordable optical recording medium) such as a DVD-R or a DVD-RW, which is capable of recording information thereon, information is recorded by forming pits.
When recording information, laser pulse control, which is called “write strategy” (recording strategy), is used in order to accurately record pits on the order of submicrons, which pits are generated by thermal recording. This recording strategy is for enabling reproduction of a correct signal at the time of reproduction by conducting correction as described below. If a pit is formed while power corresponding to the pit length is sustained, a longer pit is actually formed by remaining heat resulting from a laser beam. Correction for this, and correction for a deviation in pit length caused by a difference in properties of the recording layer or a signal combination are conducted.
FIG. 5 shows this recording strategy in the case of an 8T signal. A portion P (write data signal) for forming a pit in this recording strategy includes a top pulse (Ttop) having a front edge that lags behind a rising edge of a write signal (recording data:recording signal) by 1T or more and having a large pulse width, and five multipulses (Tmp) each having a pulse width smaller than that of the top pulse (those pulses are referred to as write pulses).
As examples of the recording strategy shown in FIG. 5, various recording strategies are known. Those recording strategies are suitably used in optical information recording on DVDs or the like (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2002-150563).
However, if one attempts to apply such a strategy to an optical information recording media, which has a narrower track pitch and higher recording density than DVDs, it is difficult to form desired recording pits, and degradation in recording properties, such as jitter increasing, is observed.
The present invention has been achieved in order to solve the above-described problems.
It is an object of the invention to provide a signal output method capable of forming pits having stable shapes on an optical information recording medium having a narrower track pitch and a higher recording density as compared with conventional DVDs, and of reducing jitter in the reproduced signal, and to provide an optical information recording medium having information recorded thereon by the signal output method.